Capacitive lighting system



Feb. 24, 1953 w. B. GREENLEE CAPACITIVE LIGHTING SYSTEM 2 SHEETS-SHEET lFiled May 10, 1948 IllIlI/IA H INVENTOR. William B. Greenlee ATTORNEYFeb. 1953 w. B. GREENLEE CAPACITIVE LIGHTING SYSTEM 2 SHEETS-SHEET 2Filed May 10, 1948 INVENTOR. William B. Greeplee ATTORNEY Patented Feb.24, 1953 UNITED STATES ATENT OFFICE CAFACITIVE LIGHTING SYSTEM WilliamB. Greenlee, Peru, Ind.

Application May 10, 1948, Serial No. 26,037

4 Claims.

My invention is directed to capacitive lighting systems, particularly tothose employing high frequency alternating current for illumination ofgaseous discharge lamps, and has as an important object the provision ofan efiicient high frequency lighting system operable by relatively lowvoltage current, which is adapted to yield pleasing decorative effectsas well as greater light intensity, and in which the'high frequencyradiations are effectively confined.

Other important objects include the provision of novel gaseous dischargelamps and devices for disposing such lamps in energy transmittingrelation to high frequency fields, as well as devices for establishing ahigh field gradient for energy flowing through the lamps.

Other objects reside in the diverse novel shapes, combinations, andarrangements of component parts, as will more fully appear in the courseof the following description and from the appended drawings in which:

Figure I is a vertical sectional view of a lamp and conductor;

Figure 2 is a plan view of. a series of lamps similar to thoseillustrated in Figure 1, arranged on a conductor;

Figure 3 is an elevational View of the lamp string illustrated in Figure2 applied to a tree;

Figure 4 is a partially sectioned vertical elevation of another form oflamp together with a suitable socket;

Figure 5. is a partially sectioned elevation illus mating the assembledposition of the parts shown in Figure 4;

Figure 6 is a partially sectioned elevation through-a modified form ofmy lamp.

Figure '7 is an elevation illustrating the 2.556111 bled position of theparts shown in Figure 6;

Figure 8 is a partially sectioned perspective view of a modified form ofmy invention, particularly adapted for use as a sign; and

Figure 9 isa partially sectioned elevation of a modified form of mydevice as applied to tree decoration.

In Fig. 1 I have illustrated a lamp, generally designated H5, which mayinclude a hollow spherical glass envelope ll, having sealed therein aglass conduit i2 provided with an internal bore, indicated at It. Theenvelope H is filled with a suitable gas, such as neon, argon, krypton,helium, xenon, or mixtures thereof under low pressure, although othergases may be employed, if desired. Preferably, the internal surface ofthe envelope 1 l is provided with a coating of suitable phosphor M ofthe type adapted toradi- 2 ate visible light waves when acted upon byultraviolet radiation. The surfaces of the conduit l2 preferably shouldnot be coated with a phosphor, although in special instances such acoating may be employed.

A high frequency conductor 16 extends through the bore it of the conduitI2, the lamp Ill being held in position on the conductor It by asuitable resilient grommet ii, shaped to resiliently engage theconductor l6 and the internal surfaces of the bore 93. The grommet I!should fit both the bore 13 and the conductor l6 quite closely in orderto prevent the entry of water or moisture into the bore It. Theconductor I6 is normally provided with an insulating coating l8 whichneed not be removed from the portion of the conductor extending throughthe bore I3 and serves to insulate the conductor I6 from an externalconductive screen or mesh covering i9.

As best seen in Figure 2, the covering l9 may extend over the conductorit and the lamps H] which may suitably be spaced at intervals along theconductor. This covering i9 ordinarily comprises a metallic mesh orscreen of a highly flexible nature and open weave, formed by weavingfine wire or the like. It is essential to my purposes that the weave ofthe covering Ill be sufficiently open to permit the substantiallyunobstructed passage of light, and is, for that reason, herein termedtransparent, although it will be understood that the actual metallicmembers of the covering :9 are not themselves'transparent.

My lamp string, illustrated in Figure 2, may be applied as an assemblyfo decorative purposes, as to a Christmas tree, and connected to asuitable oscillator 26 which, in turn, is connected to a suitable sourceof alternating current and may, if desired, include an artificialground, to which the conductive covering it is connected. Alternatively,the chassis of the oscillator 2! may be connected to ground, and thecovering i9 connected to the chassis of the oscillator. It is, ofcourse, not essential that the covering H) be connected directly toground since suitable conductive media insulated from the high frequencyconductor is may be employed for this purpose. I have found shieldedcable, comprising an internal high frequency conductor it, anintermediate insulating coating 58, and an external flexible metalliccover 22 to be highly satisfactory-for this purpose.

As a more specific example, the string of lights illustrated inFigures'z and 3 may be approximately 12 feet in length and provided withapproximately 24 lights spaced evenly along the conductor. Theoscillator 2| may suitably be of an output frequency of approximately100 kilocycles at 1,000 volts. Under these conditions, when the externalcovering I3 is suitably applied over the lamps l0 and grounded, ashereinbefore described, the lighting system will draw approximately 8watts.

From the foregoing, it will be understood that as the oscillator 2|applies high frequency current to the conductor [6, a field of similarfrequency is created around the conductor and the lamps Ill disposedalong the conductor pick up this energy, causing an internal gaseousdischarge within the lamp, the intensity of the discharge beingproportionate to the field gradient through the lamp. The circuit iscompleted through the external conductive covering I9 to ground, itbeing understood that the covering [9 is at all times insulated from thehigh frequenc conductor H5. The conductor IS, in other words, acts asone element of a capacitance, the other element being the externalconductive covering l9, and the lamps ID acting as the discharge pathbetween the capacitive elements of the system.

Preferably, the lamps [0 should be disposed as closely as possible tothe conductor [6 and the covering IS in order to obtain the maximumfield gradient through the lamp. The lamps l6 assembled in the mannerdescribed are particularly well adapted for use out of doors, whereextreme moisture conditions may be encountered. I have found thatmoisture has little or no effect upon this system if excluded from thebore l3 by the resilient grommets l1. Since the covering [9 isconductive, an efficient system is provided wherein substantially all ofthe energy consumed is utilized in illumination, and furthermore thehigh frequency radiations are confined to the space within the coveringl9, thereby preventing local radio interference.

It is not, however, necessary that the covering l9 envelop both theconductor I6 and the lamp I0. As shown in Figures 4 and 5, I may providea lamp, generally designated 23, having a projecting hollow stem 24provided with indentations 26 near a hollow envelope 21. The envelope2'. contains a quantity of gas under low pressure, similar to the gasfill previously mentioned, and may also be provided with a phosphorcoating M on its internal surface. A transparent external conductivecovering 28 extends around the envelope 21 and is secured to a metalring 29 telescoped over the stem 24 and supported by the envelope 2?below the indentations 26. The lamp 23 is adapted for reception by asocket, generally designated 3 l, which is provided with a centrallydisposed internal metal clip 32 having lips 33 shaped to receive andengage the indentations 26 in the stem 24 of the lamp 23. A hollowcylindrical insulating member 34 is telescoped over the clip 32 andsecured, as by a rivet 36, to an external cylindrical metal cover 31having lips 38 extending downwardly and outwardly beyond the extremitiesof the clip 32 a distance sufiicient to firmly engage the metal ring 29when the lips 33 of the clip 32 have engaged the indentations 26 in thestem 24. The conductor [6 extends through the socket 3| into contactwith the clip 32, but is insulated from the cover 31. Since shieldedcable should be used for this type of insulation, the externalconductive covering 22 of such cable is secured to the cover 31 of thesocket 3 I. Therefore, as high frequency current is applied to theconductor I6, the lamp 23 will be illuminated, the current flowingthrough the clip 32 and the lamp 23 to the covering 28, through the ring29 to the covering 31', and then through the external cover 22 toground, completing the circuit and confining the high frequency field tothe desired area.

It is, of course, not essential that the envelope 2? of the lamp 23 bespherical in shape, since substantially any other shape will be foundsuitable. If desired, the envelope may be formed as letters of thealphabet or numerals, and emp-loyed for advertising purposes. In suchinstances, however, the modified form of apparatus illustrated inFigures 6 and 7 are usually more efficient. In this modification Iprovide a tubular envelope 39 supported within a transparent externalconductive covering 4( by a suitable conductor 42 secured at one end tothe envelope 39 and at the other to a metal clip 43, having indentations26 similar to those described in connection with Figure 4. The clip 43and the con ductor :52 may be embedded in a cylindrical block M ofinsulating material mounted within an annular metal ring 46 which is, inturn, secured to the external covering 41. Although the clip 43 mayassume many various forms, I have illustrated my preferred form which issimilar to that previously described and employs a similar socket. Theenvelope 39 is, as in other lamps previously described, provided withgas fill, and, if desired, an internal phosphor coating. Maximumefilciency will be obtained by securing the conductor 42 to the envelope39 at a point somewhat less than half way along the envelope and r byproviding a conductive member 41 connected to the external covering 4|extending upwardly along the envelope 39 for a substantially equaldistance. As the conductor I6 is energized, the energy will flow throughthe clip 43 and along the conductor 42, through the lamp and into thecovering 4! through the conductor 41, the latter being effective toconfine substantially all of the energy flowing in the circuit to a pathwhich includes the lamp. It is, of course, essential that the conductor41 and the external covering 4| be spaced or insulated from theconductor 42. By the use of suitable insulating material disposedbetween the covering 4! and the conductor 42, the covering 41 may bebent inwardly toward the lamp below the conductor 42, therebyeliminating the desirability of the conductor 41. This does not,however, constitute a preferred embodiment. The envelope 39 may, aspreviously mentioned, assume substantially any desired shape, as may thetubing employed in the construction of the so-called neon signs, andmay, by the suit able selection of phosphors and gases, provide a widerange of color selection. The external covering which constitutes on ofthe capacitive elements of my system need not, in each instance, beemployed in precisely the manner described, it being desirable, however,to dispose the covering in such a position that the lamp employed willbe supported in relatively close proximity thereto. An example of thistype of installation is shown in Figure 8, in which I have provided asign comprising a generally rectangular box, generally designated 48,having sides 49 and a bottom 5!. A metal plate 52 may be disposed withinthe box between the sides 49 and spaced from the bottom 5!. The plate 52is provided with a plurality of spaced openings 53 suitably shaped toreceive tubular gaseous discharge lamps 54. If desired, spring clips 56may .be secured to the underside of the plate 52 to limit the projectionof the lamps 54 through the plate. An external transparent conductivecovering 5'! enveloping the box 48 is provided and connected to ground.The oscillator 2! is connected by a suitably shielded conductor 55 tothe plate 52.

When properly arranged the lamps 54 should project through the plate 52for approximately one-third to one-fourth of their length and should besufficiently long to bring the outer ends thereof into close proximitywith the external covering 51, thereby insuring that substantially allof the energy flowing between the plate 52 and the covering 5'! goesthrough the lamps 54.

A similar arrangement may also be employed in tree decoration or thelike, utilizing lamp strings of the type illustrated in Figure 2, butwithout the external covering l5. In such instances, as illustrated inFigure 9, the lamp strings may be draped on the tree or other supportnear the outer ends of the boughs, and the entire tree covered with atransparent conductive esh cover 59 suitably connected to ground.

From the foregoing, it may be seen that in each instance the lampsemployed are disposed in energy transmitting relation to both the highfrequency conductor and the external conductive covering, thisdisposition not only insuring a high field gradient through the lamp butalso confining the high frequency field to the desired area. Since nointernal electrodes are employed, relatively impure or inexpensive gasesmay be employed, and the simplicity of construction makes possible notonly inexpensive fabrication but permits a high order of durability.Because of the eflicient coupling between the capacitive elements of mylighting system, substantially all of the energy consumed is utilizedfor illuminating purposes, resulting in a light of higher intensity thanwould otherwise normally be expected.

The foregoing detailed description has been made in compliance with R.S. 4888 but is not intended to limit my invention to the precise detailshereinbefore described except in so far as defined by the appendedclaims.

I claim:

1. A gaseous discharge lamp assembly comprising a transparent envelopeof dielectric material having its interior sealed from the atmosphere, aconduit extending through the envelope and sealed at each end to theenvelope, a rare gas sealed within the envelope at low pressure andencompassing the conduit, a high fre-- quency conductor extendingslidably through the conduit, means between the conduit and envelope forholding the envelope in place on the conductor, and a groundedreticulated metal member around the envelope.

2. A gaseous discharge lamp assembly comprising a hollow transparentglass envelope having its interior sealed from the atmosphere, a glasstube extending through the envelope, said tube being sealed at each endto the envelope, a rare gas sealed within the envelope at low pressureand encompassing the conduit, a. high frequency conductor extendingslidably through the glass tube, means extending between the conductorand the glass tube for holding the envelope in position on theconductor, and a grounded reticulated metal member enveloping theconductor and the envelope.

3. A gaseous discharge lamp assembly comprising a spherical glassenvelope having its interior sealed from the atmosphere, a straightglass tube extending diametrically through the envelope and sealed atits opposite ends to the envelope wall, a rare gas sealed within theenvelope at low pressure and encompassing the conduit, a high frequencyconductor extending slidably through the glass tube, means extendingbetween the tube and the conductor for holding the envelope in place onthe conductor, and a grounded reticulated metal member enveloping theconductor and the envelope.

4. A gaseous discharge lamp assembly comprising a transparent envelopeof dielectric material having its interior sealed from the atmosphere, atube of the same material extending through the envelope in sealedopposite ends to the envelope, a phosphor coating on the internalsurfaces of the envelope, a rare gas sealed within the envelope at lowpressure and encompassing the tube, a high frequency conductor extendingslidably through the conduit, means extending between the tube and theconductor for holding the envelope in place along the conductor, and areticulated grounded metal member completely enveloping said conductorand envelope.

WILLIAM B. GREENLEE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,819,105 Machlett Aug. 18, 19312,004,577 Lebedenko June 11, 1935 2,117,544 Coustal May 1'7, 19382,268,870 Greenlee Jan. 5, 1942 2,457,503 Singer Dec. 28, 1948 2,484,332Capita Oct. 11, 1949 FOREIGN PATENTS Number Country Date 324,101 GreatBritain Jan. 17, 1930 354,273 Italy Nov. 16, 1937

